Housing prices in the GTA have ballooned by 20 per cent over the last year, with Richmond Hill and Oshawa showing the largest gains, according to a housing survey released Tuesday by Royal LePage.

The survey found an increased demand in suburban areas outside downtown Toronto, with Richmond Hill and Oshawa leading the way. Home prices in those areas have risen by 31.5 per cent and 28.2 per cent, respectively.

Royal LePage says the surge in Richmond Hill was the largest in the country.

"I've not seen anything that high before, ever," said Dianne Usher, senior vice-president at Johnston and Daniel, a division of Royal LePage.

Across the GTA, the average price of a single-family home is now $759,241. Condo prices also increased by 11 per cent, pushing the average price to $408,908 over the last year.

Royal LePage says the unrelenting gains are now driving prices up not only in the Golden Horseshoe, but as far away as London and even Windsor, Ont.

"We believe the market will continue to be strong, continue to be a sellers' market, certainly in the short term," added Usher, who said the preferred solution within the real estate community is to boost supply by loosening restrictions on and increasing density.

"We feel that the price increases are not sustainable, and if left alone, the market will correct itself," Usher said.

Toronto vs. Vancouver? No contest

The nationwide survey also found that prices in the previously smouldering-hot Vancouver market are beginning to decline, leaving the GTA as Canada's undisputed real estate madhouse.

"For the first time in several years, real estate markets in Vancouver and Toronto are headed in opposite directions," said Phil Soper, president and CEO at Royal LePage.

The survey was the first since 2013 to record a decline in home prices in Greater Vancouver.

Royal LePage says other areas of the country displayed a healthier mid-single digit price increase.

"The trend in Alberta, Quebec and Atlantic Canada is particularly encouraging," said Soper. "Our concerns with the state of Canadian real estate begin and end with Toronto and Vancouver."